High frequency coupling device

ABSTRACT

A device for coupling high frequency signals, utilizing a noninductive spring member fabricated from solid tubular material wherein slots are made through a substantial portion of the tubular material in planes orthogonal to the axis of the tube, with successive cuts originating at different radial locations.

I Umted States Patent 11 3,660,804 Bebber, Jr. [4 1 May 2, 1972 [54] HIGH FREQUENCY COUPLING DEVICE 1,351,676 8/1920 Myers ..151/21 1,499,873 7/1924 Ravier ..151/38 X [721 lnvenm" Cmmaek, 2,757,351 7/1956 Klostermann ....339/177 [73] Assignee: The North Microwave Corporation, Plainview, NY. Primary Examiner-Richard E. Moore Anomey.lames A. Eisenman, John C. McGregor and Robert [22] F1led: Apr. 17, 1968 Snack 21 A 1. No.2 722 006 1 pp 57 ABSTRACT 52 us. c1 ..559/177, 85/50, 151/38 A device for p g g equenc signals, utilizing a non- [51] ""0". 13/24 inductive spring member fabricated from solid tubular materi- [58] Field oISearch ..85/50 AT; 151/21 0, 3s; 31 wherein Slots are made lhroush a Substantial Portion of the 339 77 43 255 tubular material in planes orthogonal to the axis of the tube,

with successive cuts originating at different radial locations.

[56] References cued 3 Claims, 7 Drawing Figures UNITED STATES PATENTS 326,345 9/1885 Taylor ..51/38 I! I0 17 26 F w 32 l ,s-

" 7 I X /l 31 22 PATENTEDMAY 21912 3,660,804

Ma 2% 54W ATTORNEY! HIGH FREQUENCY COUPLING DEVICE BACKGROUND OF THE INVENTION In the fabrication of coupling devices for high frequency applications such as coaxial couplings, it is necessary to provide extremely close tolerances in the dimensions of the unit and it is also necessary to insure the absence of undesirable electric circuit paths. It is important that surface contact be good and where the coupling is contemplated for use in a manner that includes frequent make and break arrangements, it is important that the unit be capable of assuming a good coupling condition repeatedly and reliably.

In a specific utilization of the present invention, it is contemplated that the coupling devices will be employed in a turret arrangement wherein a plurality of devices are radially mounted for rotation about an axis. In this arrangement, the devices of the invention are selectively brought into mating contact with a stationary circuit coupler. The free end of each device is then attached to any desired circuit arrangement. Thus, for example, a complete unit utilizing a plurality of devices according to the invention may take the form of a turret attenuator wherein each of the devices is associated with a particular attenuator and rotation of the turret will permit coupling of the particular attenuator into a circuit.

An essential feature of the present device resides in the structure of a resilient member for urging the outer coaxial conductor of the coupler into contact with the mating conductor of a stationary coaxial conductor. Obviously, this is a function required in many coupling devices of this type. The springs used to perform this function must conform to critical dimension requirements and the spring constant must be reliable and determinable. Furthermore, the springs must be extremely resistant to fatigue inasmuch as they may be subjected to varying pressure many thousands of times. Since the coupling devices contemplated by the present invention are relatively expensive and their failure may result in closing down very expensive equipment for intolerable lengths of time, it is extremely important that all of the elements of these devices are reliable.

In the past, a number of helical spring arrangements have been used. Among other difficulties in the utilization of such helical springs is the fact that they form a continuous conducting loop which may introduce extraneous inductive effects into the coupling. In addition, the dimensional stability and design criteria for such springs render them difficult to develop with repeatable accuracy. It has been known in the past to also employ a wire spring wrapped around a rubberlike core. This type of spring arrangement has some dimensional stability, however, it is subject to change with environmental conditions and also provides a continuous helical conductive loop.

SUMMARY OF THE INVENTION The present invention is concerned with devices for coupling high frequency signals. More particularly, it is concerned with such coupling devices which use spring means to insure mating contact.

It will be apparent that the development of a coupling device includes as an important factor the use of individual components that fully cooperate with all other components. As already noted, in coaxial couplings, dimensional factors are of extreme criticality. Thus, it must be possible to prepare each component within the coupling to critical dimensions, and in order to minimize the total cost of each unit it is important that the critical dimensions be obtainable with a minimum of machine and operator time. The present invention introduces a unique tubular spring wherein a series of transverse slots are made, each in substantially parallel planes and each commencing at different radial locations about the axis of the tube. The basic material of the tube may take a number of forms and the resulting spring is both dimensionally and dynamically reliable.

The spring employed in the instant invention is of constant diameter throughout its operating range and therefor is particularly convenient for use in close tolerance coaxial coupling devices. Furthermore, in compression and expansion, the spring exhibits an even distribution of force providing planar face Contact on each end. This is also an important feature in coaxial couplings because the face of the spring may at times be directly employed as part of the conducting circuitry.

It is an object of the present invention to provide a coaxial coupling device of improved form.

It is another object of the invention to provide a coaxial coupling device including a spring member that operates on the outer coaxial conductor and has improved dimensional and dynamic characteristics.

It is another object of the present invention to provide a spring member that is dimensionally stable, easily manufactured, and electrically substantially non-inductive.

In accordance with the invention there is provided a coaxial coupling comprising an inner conductor and a spring-mounted outer conductor. The spring mounting is effected with a tubular member having a series of successive slots therein, each slot being rotationally offset relative to the next in order to provide substantial equality of compression and/or expansion across the entire face of the member.

It will be appreciated that in the production of spring members of the nature used in this invention, one is dealing with extremely small members and dimensional criticality is of prime importance. When handling this type of unit, operator error becomes an important factor in fabrication cost. Actual machining is also an important factor. The springs employed in the past required precise and time consuming machining, whereas the spring members of the present invention can be quickly and easily machined and their spring constant is highly repeatable.

A more complete understanding of the present invention will become available from the following detailed description which is made in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of a coupling device of the type contemplated by this invention; 4

FIG. 2 is a cross-sectional view taken through the front portion of an assembled coupling of the type shown in FIG. 1, schematically illustrated in contact with a mating coaxial conductor unit;

FIG. 3 is an enlarged view in perspective of a tubular spring of the nature contemplated by the invention;

FIG. 4 is a side view of the spring illustrated in FIG. 3;

FIG. 5 is a front view of the spring illustrated in FIG. 3;

FIG. 6 is a perspective view of another embodiment of the spring utilized in this invention; and

FIG. 7 is a sectional view taken along lines 7-7 of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The exploded view of the coupling in FIG. 1 illustrates the principal components of the device. The main structure 10 has an outer conductor 11, with a rear portion 12 that is threaded for connection to coaxial output means. The front portion of structure 10 is adapted to receive the various components in the manner more clearly illustrated in FIG. 2. A central 'conducting member 13 is mounted along the axis of the coupling device and held in a close tolerance central position by means of an insulation mounting 24 shown in FIG. 2. The outer contacting elements of the coupler include a rear element 14 having a shoulder 15 adapted for butting contact with shoulder 26 on outer conductor 11, and a plurality of tines 16 which are biased to provide a slight radially outward pressure in order to effect good low frequency contact with contacting element 19 of the coupler. As more clearly shown in FIG. 2, the ends 17 of tines 16 project radially outwardly from the tines themselves to establish point contact with element 19. The unique spring 18 (which will be described in greater detail hereinafter) is shown between the element 14 and an outer contacting member 19. Contacting member 19 has an inner sleeve 20 adapted to encircle the tines. Element 19 also has a shoulder portion 21 and a contacting face 27. The edges of contacting face 27 are beveled in order to assist in moving this face back and forth across mating surfaces when the coupler is used in the type of turret attenuator mentioned hereinbefore.

Spring member 18 has a circular orifice therein with dimensions adapted to provide a close sliding fit over sleeve 20 of element 19. The outer diameter of spring 18 is restricted to the outer diameter of contacting shoulder 21 and both of these diameters are designed with close tolerances to come within the inner diameter of the sleeve 11. Central conducting pin 23 is spring mounted within member 13 and is axially forced toward the front of the coupling.

FIG. 3 is a perspective view of the type of spring member 18 used in this invention. This member is manufactured from a piece of tubular stock made of any material that is found to be suitable. A plurality of slots or cuts 35 through 38 are made in the tubular stock. These slots are begun at positions successively rotated about the axis of the stock in order to provide proper balancing of the spring action. As seen more clearly by consideration of FIGS. 4 and 5, in the particular spring member shown, four slots are provided in the stock and each slot is begun 90 away from the preceding cut. It will also be noted that each slot proceeds right through the stock until a point 39. This leaves a portion of material 40 about which the adjacent sections may pivot. Each slot leaves a similar portion of material and this provides both the resilience and stability of the spring.

Spring member 18 will be found to be unique not only in structure, but because of the features that are available as a result of this structure. First, it is very simple to provide a member having an accurately determined outside diameter. Second, there is little difficulty in manufacturing the member with high repeatability of characteristics. Third, planar end faces can be provided that will furnish good surface contact with mating devices. Fourth, there is no helical electrical path to create unwanted inductive effects.

The resilience of spring members developed in accordance with the teachings herein, can be controlled in many ways. Obviously, the material used will affect the spring constant and a wide variety of materials have been tested and found useable. In addition, the number,depth, width, and spacing of each slot will afiect the spring constant. Still further, the amount by which successive slots are rotationally offset will affect the spring constant. In the latter respect, suitable variations ranging upward from three slots each rotationally offset by have been found suitable.

Although the spring shown in FIGS. 3 through 5 is of particular value in coaxial coupling devices of the type herein contemplated, it should be appreciated that the principles relating thereto are also applicable to other basic forms. An example of one modification is shown in FIGS. 6 and 7 wherein a piece of square stock 41 with a hole 46 therethrough, has been employed as the basic structure. In the spring member of this embodiment, the slots are made in a manner which leaves a portion of material 48 between adjacent faces of each slot.

It should also be understood that the particular manner in which the slots terminate in order to leave material between adjacent faces is a design factor that may be varied in accordance with the ultimate design objectives. In fact, there is no essential need for an aperture within the stock employed, the spring effects being obtainable even where the material is solid.

Applicant has described a basic embodiment of the invention along with several embodiments of the unique sub-components therein. Modifications may be made within the skill of those in the art without departing from the scope and spirit of the invention.

Whatl claim is: 1. A high frequency coupling device comprising inner and outer spring biased conductors, a rotationally extending stationary shoulder, an electrically conductive material interposed between said outer conductor and said shoulder and having a constant diameter aperture therethrough, said outer conductor having an axially extending portion projecting within said aperture and a radially extending end contact portion, and a plurality of at least three slots in said material disposed within parallel planes equally spaced along the longitudinal axis of said material and rotationally oriented in equally spaced increments about said longitudinal axis.

2. A high frequency coupling device as defined in claim 1, wherein the slots in said electrically conductive material extend beyond the center thereof.

3. A high frequency coupling device as defined in claim 2, wherein said electrically conductive material is substantially tubular and has at least one planar end surface, including a conducting element with a radial portion between said shoulder and said planar end surface and an elongated axially extending portion within said aperture and in contact with said outer conductor. 

1. A high frequency coupling device comprising inner and outer spring biased conductors, a rotationally extending stationary shoulder, an electrically conductive material interposed between said outer conductor and said shoulder and having a constant diameter aperture therethrough, said outer conductor having an axially extending portion projecting within said aperture and a radially extending end contact portion, and a plurality of at least three slots in said material disposed within parallel planes equally spaced along the longitudinal axis of said material and rotationally oriented in equally spaced increments about said longitudinal axis.
 2. A high frequency coupling device as defined in claim 1, wherein the slots in said electrically conductive material extend beyond the center thereof.
 3. A high frequency coupling device as defined in claim 2, wherein said electrically conductive material is substantially tubular and has at least one planar end surface, including a conducting element with a radial portion between said shoulder and said planar end surface and an elongated axially extending portion within said aperture and in contact with said outer conductor. 